My DH never lost one of his baby teeth. Dentists won't pull it b/c they don't know if his adult tooth will come down or not, and are concerned with it causing spacing issues if they pull it. It's not a big deal at all. He has never had a cavity!

I lost all of mine, starting around 5/6 and then finished sometime in middle school. All of my teeth are rotting out of my head at an alarming rate - which I think has more to do with the crap I ate as a kid than when my adult teeth came in.